Crimped polyester filament yarn and process for making same

ABSTRACT

Polyester textile filaments which have asymmetric shrinkage properties, and may be heat-relaxed to provide a high crimp frequency and a narrow crimp frequency distribution, are produced by melt-spinning a single synthetic linear polyester composition, drawing the filaments and then passing them over an unheated nonmetallic pin at high speed. The process conditions are controlled to provide filaments of regular cross-sectional configuration having a modified minor portion, distinguishable from the remainder of the filament by a different refractive index, which extends substantially continuously along the filament.

United States Patent [191 Frankfort et a1.

1111 3,816,992 June 18, 1974 CRIMPED POLYESTER FILAMENT YARN AND PROCESS FOR MAKING SAME [75] Inventors: Hans R. E. Frankfort, Kinston,

NC; Peter F. Lyons, Wilmington, Del.

[73] Assignee: E. 1. du Pont de Nemours and Company, Wilmington, Del.

22 Filed: Apr. 23, 1973 21 App]. No.: 353,808

Related US. Application Data [63] Continuation-impart of Ser. No. 210,884, Dec. 22,

1971, abandoned.

[52] US. Cl 57/140 R, 28/7212, 28/7217,

57/140 BY, 57/140 J [51 Int. Cl DOZg 1/16, DO2g 3/24 [58] Field of Search ..57/34 R, 34 D, 140 R,

57/140 BY,140J, 157 R, 157 F, 157 MS; 28/l.4,7212,72,17

[56] References Cited UNlTED STATES PATENTS 2,974,391 3/1961 Speakman et a1. 28/7213 X 3,115,744 12/1963 Nott 28/7217 X 3,226,792 H1966 Starkie 28/7217 X 3,317,978 5/1967 McIntosh et a1... 28/7217 X 3,358,345 12/1967 Daniel 28/].2 3,379,809 4/1968 Woods 264/168 Primary Examiner.lohn Petrakes [57] ABSTRACT 14 Claims, 13 Drawing Figures .PATENTEDJuu 18 m4 SHEET 1 OF 4 FIG. 1B

Fl G.' lA

Fl 6. 2A

FIG-3A PKTENTEBJuu 1 a 1974 SHEET 2 [IF 4 Fl G- 4A FIG. 4B

FIG-5 PA'TENTEDJunIaM sum 3 nr 4 FIG- FIG.

CRIMPED POLYESTER FILAMENT YARN AND PROCESS FOR MAKING SAME REFERENCE TO RELATED APPLICATION This is a continuation-in-part of copending application Ser. No. 210,884, filed Dec. 22, 1971 now abandoned.

BACKGROUND OF THE INVENTION The present invention is concerned with asymmetric polyester filaments and the crimped products obtained by heat-relaxing them.

Filaments which crimp due to asymmetric shrinkage when relaxed have been prepared by a variety of methods. Kilian U.S. Pat. No. 3,050,82l discloses polyester filaments which have been asymmetrically quenched during melt spinning, by blowing cooling air against one side of the filaments as they emerge from the spinneret. When drawn and then relaxed, the filaments will shrink to a greater extent on one side of the filament, but a relatively low crimp frequency is obtained in this manner.

Crirnpability has been imparted by passing filaments over a sharp edge. This weakens the filament and improvements in the crimp obtained are desirable. The edge-treated side is on the inside of crimp bends. Terumichi Ono et al. U.S. Pat. No. 3,600,271 discloses that a better crimped product is obtained when previously undrawn 6-nylon is drawn over a cylindrical pin heated to about 600C. However, Yukio Mitsuishi et al. U.S. Pat. No. 3,538,566 teaches that milder conditions must be used for polyester filaments. Lower pin temperatures are used and the filaments are wet when drawn over the pin in the process of thispatent. The results obtained at various pin temperatures and filament speeds of 200 to 600 meters per minute indicate that undesirably low crimp frequencies are obtained.

Edington et al. U.S. Pat. No. 3,224,068 discloses a process in which the treatment is performed after the filaments have been drawn, so that higher temperatures can be used. As illustrated, polyester filaments are passed at speeds of up to 450 yards per minute over a strip of tungsten or tungsten carbide which is about 0.030 inch wide and heated to 365C-375C. Special heating means are used to maintain the strip at an even temperature. The relaxed product is said to have a broad range of crimp amplitudes and crimp frequencies along the filament length, and sections with no crimp at all, but to be an improvement over previous products obtained by treatment with the usual electrically heated wire. pin or bar.

Potman et al. U.S. Pat. No. 3,601,872 discloses that 6-nylon carpet yarn of increased voluminosity can be prepared by introducing two crimps separately into a yarn, a latent crimp by asymmetric treatment with a heated pin and a direct crimp by subjecting the yarn to direct crimping treatment by a gear-crimping, a stufferbox crimping, or an air-crimping treatment.

SUMMARY OF THE INVENTION The present invention provides polyester filaments and yarns which, in the heat-relaxed form, have an especially desirable crimp frequency distribution. Additionaladvantages of the invention will become apparent from the specification and drawings.

A'product of this invention is a textile filament having asymmetric properties and an abraded surface extending along one side of the filament, and consisting of a single synthetic linear polyester composition having a modified minor portion, distinguishable by a difference in refractive index, which extends substantially continuously along the abraded side of the filament. The continuity of this minor portion is such that less than 5 percent (usually less than 3 percent) of the filament length is occupied by discontinuities longer than 2 millimeters and the average length of all discontinuities is less than 2 millimeters (usually 0.6 to 1.5 mm.). The number of discontinuities longer than 2 mm. is usually less than 30 percent of the total number of all discontinuities and is preferably less than percent. In general, this minor portion occupies from 3 percent to percent usually 4 percent to 15 percent) of representative cross-sectional areas along the filament and is l to 3 microns in thickness (usually 1.4 to 2.6 a), measured from the abraded surface.

The abraded surface of the filament is generally on the outside of crimp bends and is clearly marked by closely spaced, parallel ripples which extend transversely with respect to the filament length, when viewed at high magnification, after a heatrelaxing treatment for 5 minutes in 180C. air.

A heat-relaxed product of the invention is as defined above and further characterized by crimp frequency values, measured after a heat-relaxing treatment for 5 minutes in 180C. air and normalized for 2.5 denier per filament, which average at least 25 (preferably 30 to 60) crimps per filament inch with a percent coefficient of variation of less than 30 (preferably less than 20). Preferably at least percent of the filament length has greater than 15 crimps per filament inch and the crimp frequency distribution for the middle 90 percent is numerically equal to or less than said average (usually from 0.4 to 0.9 times the average crimp frequency value). Preferably at least 90 percent of the filament length has greater than 20 crimps per inch.

The invention includes multifilament yarns of the above filaments, either before or after crimp has been developed by heat-relaxation. In the latter yarns, the filament crimp is random from filament to filament. This crimp provides a highly desirable appearance when the yarns are viewed without magnification.

A process suitable for preparing the above products at extremely high speeds is disclosed subsequently.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 4A are photomicrographs of representative portions of filaments which have been melt-spun, drawn and pin-textured, as described subsequently in examples having the samenumbers, and prior to any additional treatment. FIGS. 15 to 4B are corresponding photomicrographs of filaments produced as described in these examples and then heat-relaxed for five minutes in C. air. The filaments are viewed from the side at over 1000X magnification, the actual magnification being indicated by scales accompanying the figures( l millimeter 1000 a).

FIG. 5 is a greatly enlarged cross-sectional view of one of these filaments, the modified portion being indicated by cross hatching.

FIG. 6 is a side view of a filament at low magnification to illustrate crimps counted in determining crimp frequency.

FIG. 7 is a graph of the crimp frequency distribution DETAILED DESCRIPTION The products of this invention may consist of any of the single synthetic linear polyester compositions conventionally used in textile filaments and yarns. Preferably the polyester consists essentially of poly( ethylene terephthalate), which may be coopolymerized with minor amounts of other components to improve textile properties; such copolyesters include poly( ethylene terephthalate/isophthalate), poly(ethylene terephthaIate/adipate) and poly( ethylene terephthalate/S- (sodium sulfo)-isophthalate). Other polyesters include poly( tetramethylene terephthalate) and poly( 1,4- cyclohexylenedimethylene terephthalate). The single composition may comprise intimate mixtures of the polyesters and/or copolyesters and may contain minor amounts of other additives e.g., delusterants, antistatic agents, or other monomeric or polymeric additives).

Filaments having substantially round cross sections are preferred, but other cross-sectional configurations may be used, e.g., trilobal or octalobal.

Prior to developing the crimp, the multifilament yarn products may be of any conventional denier/filament count, preferably about 35 to 250 denier and 10 to 200, preferably 17 to 50 filaments, the yarns of 70/34 to 190/34 count being of particular interest. The crimp can be developed by conventional heat-relaxing treatments, several of which are disclosed in the patents discussed previously. In general, these treatments involve allowing the yarn to shrink freely while exposed to hot water, steam or dry heat. In the method used herein for comparing crimp frequencies of filaments, the filaments are suspended in semicircular form in a 180C. hot air oven for minutes and then allowed to cool while free from tension. Filaments which have been relaxed by other methods are also retreated by this test method to standardize crimp measurements.

Crimp frequencies are expressed herein as crimps per filament inch, rather than crimps per straight line inch of crimped length. The measurement is accomplished by extending the filament under a load sufficient to straighten the crimps without stretching the filament, marking l-inch distances along the filament, then removing the load to allow recrimping, and counting the crimps between l-inch marks. In order to compare filaments of different deniers, the measured crimp frequency values are multiplied by V d/2.5, where d is the denier per filament after 180C. treatment, to obtain normalized crimp frequency values. If the present shrinkage (S) in the 180C. oven-relaxing treatment is known, the value of d can be determined by multiplying the unrelaxed denier per filament by l S/lOO).

The characteristic abraded surface, which extends substantially continuously along one side of the filaments of this invention, provides a qualitative distinction from prior art filaments that have been modified in different ways to impart crimp. Abraded surfaces of filaments produced as described'in Examples 14 are shown in FIGS. lA-4B, wherein A is a photomicrograph of a portion of a pin/textured filament before additional treatment, and B is after heat relaxation. The location of modified filament portions is indicated in the latter by the closely spaced, parallel ripples crossing the filaments. FIG. 5 shows a typical cross-sectional view of these products wherein the modified filament portion, designated by cross-hatching, occupies about 5 to 10 percent of the cross section and is approximately 2 microns in thickness.

The crimp frequency of the filaments is most easily determined with a shadowgraph projection of the filament, using about 20X magnification. FIG. 6 illustrates such a projection, and the arrows indicate crimps counted. Care is taken to'count crimps which may appear quite small when viewed from a single direction; these may be significant when viewed in a different direction. FIG. 7 shows the frequency distributions of products produced as described in the examples and then heat-relaxed for 5 minutes in 180C. air. The normalized crimp frequency in crimps per filament inch is indicated on the abscissa, and the percent of the filament length having greater crimp frequencies is indicated on the ordinate. The distribution curves are numbered to correspond to the examples. This graph can be used to ascertain the percent of the filament length which has a crimp frequency greater than any given value. The average crimp frequency is the value where the 50 percent ordinate value intersects the curve. The crimp frequency distribution for the middle percent is the minimum crimp frequency for 5 percent minus the minimum crimp frequency for percent, which will be abbreviated R R Woven and knit fabrics containing relaxed yarns of this invention have desirable bulk, aesthetics, performance and uniformity. For example, yarns of the type described in Example 3, when relaxed in a hot air jet and then woven, yield fabrics having a high degree of suppleness and liveliness; warp-knits from similarly relaxed yarns have a soft hand, high bulk, and excellent dyeuniformity. Double-knit fabrics, prepared from the relaxed yarns of Example 2, have a high, firm bulk and excellent wash-wear performance, wrinkle-resistance, and dye-uniformity. Suitable filaments for such yarns are between 1 and 7 denier per filament. The yarns of the present invention can also be cut into staple lengths and converted to yarns or used as filling for, e.g., pillows, after developing the crimp.

PROCESS The products can be produced as illustrated in FIG. 8. Filaments 10 are melt-spun from spinneret 11, allowed to cool, pass in contact with a conventional first finish-applying roll (not shown) after converging, pass around feed rolls 12, through steam draw jet 13, over a second finish-applying roll 14 and then around draw rolls 15 which have a considerably higher surface speed than the feed rolls to draw the yarn. A traversing mechanism 16 is provided for guiding the filaments onto the draw rolls; when activated, it varies the path of the drawn filaments on the rolls and over pin 17. The drawn filaments pass over texturing pin 17 with a change of direction 0, and pass around pulling rolls 18 which provide tension over the texturing pin. If desired, the filaments can be guided to the texturing pin by an adustable idler roll (not shown) to facilitate changing the wrap angle 0 at the texturing pin in order to increase or decrease the length of pin-filament contact. The filaments pass from the pulling rolls over a postdraw finish roll 19 to wind-up 20, which cross-winds the product under a tension that is best measured shortly after the postdraw finish roll.

1n operating the process of the present invention, normal levels of finish, such as are typically used in spinning-drawing-winding operations, are used. Excess finish should be avoided so as not to have it interfere with frictional work at the pin-filament contact site.

Crimp is developed in the above product by a subsequent heat-relaxing treatment. However, the processes can be combined to produce a crimped product in one continuous operation. Instead of wind-up 20, the filaments are passed through heating means and cooled on a conveyor in relaxed condition prior to being wound up. On the other hand, the melt-spinning, drawing and pin treatment sequence can be split in various ways. The melt-spinning can be a separate operation. A conventional melt-spinning and drawing process can be used to produce yarn which is later pin-textured in a separate operation.

FIG. 9 illustrates such a separate operation wherein untwisted, drawn and packaged yarn is fed over-end to the pin-texturing treatment. The yarn passes from package 21 through tension gate 22 and over roller 23 to a pair of feed rolls 24. The yarn makes several wraps about the pair of feed rolls, proceeds to a pair of stretch rolls 25, makes several wraps about the pair of stretch rolls, passes over texturing pin 26 at a wrap angle 0, and proceeds over roller 27 to wind-up 28. The yarn passing over the texturing pin may be an inner wrap, i.e., the yarn passes from the pin back to the stretch rolls. Alternatively, the yarn may pass from the pin to separate pulling rollswithout returning to the stretch rolls.

The texturing pin preferably has a non-metallic composition which may be characterized as a durable, wear-resistant material having frictional properties similar to ceramic guides and draw-pins of types commonly used in producing uncrimped textile yarns. Al- SiMag pins (American Lava Corp.) are used in the examples. Suitable coefficients of friction are from 0.4 to 1.1 (determined as described in Example 7).

The pin diameter and wrap angle 6 should provide a filament-pin contact length of 0.5 to mm., preferably l to 10 mm. Filament speeds on the texturing pin may be 1,000 to 4,500 yards per minute or higher. The temperature of the yarn just prior to the pin should be from 25 to 100C., although temperatures up to 150C. may be used.

The preferred process is a coupled spin/draw/pintexturing process in which the yarn is drawn to have to 40 percent elongation and 8 to 16 percent boil-off shrinkage, and the amount of stretch over the texturing pin is from 2 to 5 percent. A difference between the filament tensions before and after the pin of 0.2 to 1.5 gpd. (preferably 0.4to 1.0 gpd.) and a total tension on the filaments at the pin (actually measured with the filamen ts temporarily by-passing the pin, using a tensiometer at asimilar location in the roll-toroll filament travel) of 0.5 to 5 gpd. and preferably 1.5 to 4 gpd., can be used to provide a suitable amount of stretch. The variables of percent stretch (s filament-pin contact (0) in millimeters, coefiicient of friction (I) and yarn temperature (t) in C. just prior to the pin, should be adjusted to give a value for (s) ('c) (fl n 10 which is from 7.5 to 35.

A EVALUATION PROCEDURES Photomicrographs of Filament Surfaces A scanning electron microscope SEM) is used to study the nature of the abraded surface of the filaments. A short sample (about three-fourths inch long) of yarn is mounted on a standard Stereoscan stub inch diameter aluminum stub). Two strips Va inch X A inch) of double-faced adhesive tape are fixed 1/2 inch apart and parallel to each other on the stub surface. The sample of yarn is lightly teased to separate the filaments, and each yarn end is fixed to one strip of the adhesive. When mounting crimped yarn, no tension is applied so that the yarn is mounted with its crimp undisturbed. Silver circuit paint is dabbed on both ends of all filaments and on the adhesive tape to insure electrical continuity to the specimen stub. The final step of specimen preparation involves the vacuum evaporation of a /40 Au/Pd coating onto the surface of the sample and stub which insures electrical continuity over the entire stub. The thickness of this coating is estimated to be of the order of 300-400 A. which is below the level of resolution of the SEM used; thus, the coating is not seen when viewing filaments by this technique.

The stub is placed in the specimen holder and after evacuation of the specimen chamber, the specimen is viewed in the SEM. Typical viewing conditions are 20 KV electrons with a beam current of 200 pamps, and a specimen tilt of 30 relative to the impinging electron beam. After areas of the filaments exhibiting modified surfaces are located, micrographs are recorded at, e.g., 200, 500, 1,000 and 2,000X magnifications. This series of magnifications includes a sufficiently low magnifica tion to illustrate the position of the modified surface relative to the crimp and a sufficiently high magnification to reveal details of the modified surface.

When viewed by this technique, unrelaxed filaments of the present invention exhibit a frictionally modified surface running along the filament length; in the relaxed filaments, this surface can be seen to be present alongthe outside of the crimp bend and can'also be seen to-have a plurality of ripples which are visible on the abraded surface and run transversely with respect to the filament length. In the jet-screen-relaxed filaments, the modified surface also runs generally on the outside of crimp bends, but may occasionally be seen on the inside where secondary folds have been imposed on sections of the filament by jet-screen impact. Continuity of the Modified Portion Interference microscopy is used to determine the continuity 'of the modified portion along filament length L, where L is taken as 40 mm. times the number of filaments in the yarn for any yarn having 34 filaments. For other yarn counts, a total of 1,360 mm, distributed uniformly across the yarn, is viewed.

When working with a 34-filament yarn, a 60 mm. length is cut from the yarn. The individual filaments are separated. Each 60-mm. long filament is taped on a glass slide so that it lies straight and the slide is im mersed in Refractive Index Fluid of an index of refrac tion (n) which matches the index of I refraction (n perpendicular) of the unmodified portion of the filament for light vibrating perpendicular to the fiber axis e.g., a fluid of n 1.540 is used for poly( ethylene tere phthalate). The filament, after immersion in the fluid,

is then covered with a second glass slide and the assembly is placed on the stage of the interference microscope. Using a suitable device, the assembly is advanced across the viewing area so that a continuous 40 mm. length is viewed at 200x.

The presence of a modified portion is detected by interference contrast i.e., the modified portion will be of different color than the remainder of the filament) or by fringe field (i.e., a fringe shift indicates a change in index of refraction going from modified to unmodified areas of the filament). Only those sections where a color difference or a fringe shift can be positively identified are considered as modified. Once a modified portion is detected, its path is followed along the filament length and the number and length of all discontinuities in its path are recorded. For convenience, a calibrated eyepiece, such that at 200K each division on the eyepiece equals is used and the length of the discontinuities is reported in divisions and later converted to mm. by the formula:

mm. (number of divisions)/( 1,000) X 5 The following are determined: M total number of all discontinuities N number of discontinuities greater than 2 mm. (2

mm. 400 divisions) U sum of the lengths of all discontinuities, ex-

pressed in mm. V sum of the lengths of discontinuities greater than 2 mm., expressed in mm. L total filament length viewed From these values, the following are calculated: Average length of all discontinuities U/M Percent of long 2 mm.) discontinuities N/M X 100 Percent of filament length occupied by long 2 mm.) discontinuities V/L X lOO The products of the present invention have a low average length for all discontinuities, and the long discontinuities, if present, occupy only a very minor portion of the total length of the filament. It is believed that these factors contribute significantly to the desirable crimp of the products, since the presence of the modified portion correlates well with the development of crimp in the filaments. Dimensions of Modified Portion: Views A cross-section of the yarn sample is suitably prepared for microtome sectioning, e.g., a yarn bundle is mounted in a Beem capsule and embedded with epoxy (Maraset" from Marblette Corp.). After trimming the cured stub, approximately 6 micron thick sections are obtained using a rotary microtome (Spencer Model 860) with a steel blade. The sections are placed onto the two halves of a cut microscope slide (insures constant thickness for a two beam Leitz Transmission Interference Microscope). The two"- specimen slides are completed by immersing the sections in refractive index oil (Cargille Index of Refraction Fluid N 1.530) and covering with microscope cover slips.

One specimen slide is placed onto the reference beam stage and the other slide is placed onto the sample beam stage of the two beam Leitz Transmission Interference Microscope. The specimen section is viewed at SOOX magnification. Following the alignment procedures, the fringe field is obtained in the field of view in white light. The fringes are then fluffed out" to obtain Cross-Sectional interference contrast, i.e., the fringes are taken to their maximum separation. The specimen section is brought into sharp focus and the index variation across given textured filaments cross-section is recorded on color film as the retardation or color difference across the filament section. The procedure can be carried out in monochromatic illumination and recorded on black and white film. The procedure described above is performed without the analyzer in the optical system and is used as a qualitative detection technique for presence of the modified portion of different refractive index.

Thickness of the modified portion is determined from 1,000X micrographs of cross-sections by measuring the thickness of the ribbon on three corss-sections at three points each, and averaging the nine values. Referring to FIG. 5, the 3 points measured are (l) the thickness at the center of the modified, i.e., cross-hatched portion and (2) and (3) the thickness near each of the extremes of the modified portion, measured at a distance of about 1 mm. from each extreme. A small plastic ruler is most conveniently used, and 1 mm. 1 ,u..

The width of the modified portion at its widest point and the diameter of the filament are measured on 1,000X micrographs of cross-sections using a suitable ruler. Four or five cross-sections per sample are analyzed; and the average of the 4 or 5 determinations is recorded. The width as percent of filament diameter is calculated by dividing the average width by the average filament diameter and multiplying by 100.

The percent area of the modified portion is determined by making a lOOOX photomicrograph, cutting out 8-l2 cross-sections from it, and weighing the filament cross-sections before W and after (W cutting the modified portion therefrom. Area (W,, W (IOO/W when W and W,, are total weights in grams, before and after cutting.

Crimp Frequency Distribution For a yarn having at least 17 filaments, a SO-cm. length of yarn is cut from the yarn to be tested, and I7 filaments, taken at random, are carefully separated from the cut length, taking care not to stretch the filaments. One filament at a time is relaxed as follows: The filament is suspended by attaching both ends to a glass rod at a sufficient distance apart to permit the filament to shrink and crimp fully without becoming taut; this is done, e.g., by attaching masking tape or a suitable clip to each end of the filament and clipping each end to the rod. The rod may be permanently mounted in the oven or placed in the oven, with the filamentalready attached to it. In either case, care is taken to have the mounted filament in a 180C. hot air (with blower at a minimum to avoid filament tangling) oven (e.g., Electric Hotpack Co., Inc., Model 1,354) for 5 minutes so that the filament is suspended and can relax freely. Then, taking care not to stretch the filament, it is removed from the oven and is carefully placed, relaxed, on a velvet board. After removal of each specimen, the oven is allowed to come back to lC. (e.g., 5 minutes) before the next specimen is palced in the oven. This is repeated until all 17 filaments have been relaxed, individually.

One end of each relaxed filament is taped to one end of the clear plastic straight-edge which has been marked off at l-inch intervals. A weight, sufficient to straighten the crimps without stretching the filament, is taped to the free end of the filament; e.g., a 0.6 g.

weight is normally satisfactory for about 2 to 6 dpf filaments, i.e., 0.15 gpd for 4 denier and 0.3 gpd for 2 denier filaments. The straight-edge is lifted to a vertical position, allowing the filament to hang freely under the tensioning weight. The filament is then taped to the straight-edge near the weighted end, while under tension. With a black felt-tipped marking pen, twelve consecutive l-inch sections are marked off on the filament. The filament is then removed and taped at its ends, relaxed, on a second, clear straight-edge. The markings on the filament areduplicated on the second straightedge along side of the filament with a black felt pen. This allows direct measurement of the crimps per filament inch. The number of crimps between the markings are counted at about 20X magnification using a shadowgraph (e.g., Nippon Kogaku K.K., Japan, Model 6). Crimps per each filament inch cpi) for a total of 204 one-inch filament sections per sample are recorded 17 filaments X 12 one-inch sections).

1f the yarn contains less than 17 filaments total, a sufficient length of yarn is used, so that the number of filaments times the length equals 204 inches.

The number of one-inch sections in each of a series of crimp ranges (-5 cpi, 6-10 cpi, 11-15 cpi, etc., in increments of cpi/range) is counted and the percent of filament length within a given crimp range is calculated by:

Number of l-inch sections in given crimp range X 100/204 sections Data are reported in terms of filament length present, having a crimp frequency greater than a given level, using as levels the upper limit of each crimp frequency range, i.e., 5 cpi, cpi, cpi, etc. The respective observed crimp frequency vaules are multiplied by V d/2.5 to obtain normalized crimp frequency values, where d is the denier per filament after the heatrelaxing treatment in 180C. air for 5 minutes. Any accurate method can be used for determining d. The method used herein is to multiply the denier per filament before the heat-relaxing treatment by (1 S/l00), where S is the percent shrinkage calculated from yarn lengths before and after the heat-relaxing treatment when measured under sufficient tension to just straighten any crimps without stretching the yarn (a tension of 20 grams is suitable for 34-filament yarns in the Examplesunless otherwise specified).

Illustrative data for one of the examples (Ex. 2) is given below:

Crimp Range No. of l-inch 7t Filament (cpi) (d dpf] Sections Length Present 0 s 0 6-1O 0 0 I l-l5 0 0 16-20 (1 0 21-25 l 0.5 2630 15 7.3 31-35 56 27.4 36-40 73 35.7 4l45 48 23.5 46-50 1 l 5.4

The above data may be expressed as follows:

Crimp Level Crimp Level (d dpf) (Normalized for 2.5dpf) 100% Filament length with crimp frequency 5 cpi 7.5 cpi 100% l0cpi 15 cpi 100% 15 cpi 22.5 cpi 100% 20 cpi 30 cpi 10 99% 25 cpi 37.5 cpi 92% 30 cpi 45 cpi 65% 35 cpi 52.5 cpi 29% t 40 cpi 60 cpi 5% 45 cpi 67.5 cpi 0% 50 cpi cpi where normalization is obtained by multiplying the crimp frequency at d dpf by V dl2.5 and d is obtained from the following formula:

d dpf before heat-relaxing; X l S/ 100) /34) (1 21/100) and the normalization factor is:

V d/2.5= V 5.5/2.5= V 2.2= 1.5

The above determined data are plotted on a graph as percent filament length with crimp frequency greater than vs. crimp frequency level, normalized for 2.5 dpf"; this graph can then be used to ascertain percent filament length with crimp frequency greater than any age crimp frequency is equal to or less than 1.

The percent coefficient of variation is defined as the standard deviation of the individual determinations of crimp frequency (F), times 100 and divided by the av erage crimp frequency in crimps per inch. The standard deviation is calculated by the formula:

Standard deviation 2 FlN [ZF/ where N is the number of determinations. A percent coefficient of variation which is less than 30 indicates a narrow crimp frequency distribution and a value less than 20 indicates a highly uniform crimp.

In the following examples, which illustrate preferred processes for preparing the products, tensions in grams per denier gpd) are based on denier after pin textur ing, and, unless'otherwise specified, are measured with a schmid'tawaldkraiburg tensiometer (0-1000 gram scale). 1

In the Examples, unless otherwise specified, a yarn finish is applied by conventional means i.e., 1st and 2nd finish applying rolls; referring to the discussion ofFlG. 8), this finish (noted hereinafter as finish A) is a 3.9 percent aqueous mixture containing 49 parts of isocetyl stearate, 24.5 parts of sodium di-( 2-ethylhexyl)sulfosuccinate, 24.5 parts of the condensation product of 1 mol of stearyl alcohol with 3 mols of ethylene oxide, 1 part of triethanolamine and 1 part of oleic acid. It is applied at a total level (i.e., after the second finish roll) of approximately 0.3 $0.] weight percent finish on yarn after drying, based on the weight of yarn.

Just before wind-up, (at roll 19, referring to P16. 8) the yarn is treated with another conventional finish (noted hereinafter as'finish B) which is an aqueous mixture containing 20.5 parts of sulfated peanut oil, 1.8 partsof diethylene glycol, 1.8 parts of KOH, 62.6 parts of the ester formed from l-butanol and a 45-55 mixture of stearic and palmitic acids, 8.2 parts of oleic acid, 3.4 parts of triethanolamine, and 1.7 parts of ortho phenylphenol. This second finish is applied to give a total of 'A plus B of about 0.5 i 0.15 percent finish on the yarn after drying.

EXAMPLE I This example illustrates production of the products by a continuous process for melt-spinning, drawing and pin-texturing yarn as shown in FIG. 8. Specific process conditions are given in Table 1. The draw rolls are located in a draw box maintained at the indicated temperature. Properties of the product are given in Table 4. Crimp frequency distribution is shown in FIG. 7.

EXAMPLE 2 A yarn is melt-spun, drawn and pin-textured as in Example l, but using the specific conditions given in Table l. The yarn is then fed at about 3,000 ypm to a hot air jet device which deposits the yarn on a screen drum as illustrated in Clendening US. Pat. No. 3,217,386. The jet device is of the type disclosed in Coon US. Pat. No. 3,525,134 and is supplied with hot air at 335C. and 100 pounds per square inch gauge pressure. The jet device comprises a longitudinal yarn passage terminating in a short length having a width 4', of 0.033-inch and a depth of 0.030-inch; a throat region having a width d, of 0.045-inch; an expanding treatment chamber whose sides diverge at an angle ,8

of 4.5 degrees from the throat region to a width d. of

0.22-inch at the chamber exit; and dual fluid conduits, each having a width d of 0.025-inch, disposed on either side of the yarn passage and intersecting the throat region at an angle a of The dual fluid conduits and the yarn treatment chamber have the same depth of 30 0.060-inch.

The heated air supplied to the jet device forwards the yarn through the treatment chamber, plasticizes it and propels it against a screen surface on a rotating relaxing drum. The screen drum surface is of -mesh, located mils from the jet exit and revolving at 700 feet per minute. The treated yarn is taken from the screen drum at about 2,200 yards per minute by a pair of rolls and proceeds at 20. grams tension to a wind-up for packag ing. Further process details for the jet-screen-bulking step are given in Table l-A. The properties of the final product are given in Table 4 and the crimp frequency distribution is shown in FIG. 7.

EXAMPLES 3 and 4 Yarns are melt-spun, drawn and pin-textured as shown in FIG. 8, using the specific process conditions given in Table 2. The reduced wrap angle 0 is provided by guiding the filaments to the texturing pin with an adjustable idler roll. Properties of the products are given in Table 4 and the crimp frequency distributions are shown in FIG. 7.

EXAMPLE 5 This example illustrates production of the product frompreviously drawn and packaged yarn, i.e., yarn which has been melt-spun and drawn substantially as described previously, but then packaged without a tex- The feed yarn is withdrawn from the package overend and is pin-textured as shown in FIG. 9, using the specific process conditions given in Table 3. An inner wrap of yarn, lifted from the stretch rolls 25, passes over the texturing pin 26 and back around the stretch rolls before the yarn continues to the wind-up 28. Pro'perties of this product are given in Table 4.

EXAMPLE 6 This example illustrates application of the pintexturing process to fibers from polyethylene terephthalate of low relative viscosity.

Yarns are melt-spun, drawn and pin-textured as shown in FIG. 8, using the specific process conditions given in Table 5. Properties of the product are given in Table 4.

EXAMPLE 7 This example illustrates pin-texturing using a continuous high speed process with another ceramic pin and discusses results obtained with several process variations. The apparatus is arranged as shown in FIG. 8.

A series of 34-filament yarns are prepared; all having a yarn elongation of about 25 percent, a boil-off shrinkage of about 1 1 percent, and a denier of about 125.

Each yarn is subjected to pin-texturing at several speeds. The yarn is treated with a cream AlSiMag pin (No. I92, smooth finish, non-conductive as sold by American Lava Corporation, Chattanooga 5, Tenn.) at 2,050 ypm. Process data is given in Table 6. Tensions are measured using a Rothchild tensiometer having rolling guides with high speed bearings on the tension head (0 to 1,000 grams tension range).

In separate tests, it is found that the coefficient of friction, as measured by the technique described by J. S. Olsen in Frictional Behavior of Textile Yarns, (Textile Research Journal, Vol. 39, No. 1, January, 1969), using a 6 gram input tension and a 500 ypm speed, is 0.56 and the highest temperature at the pinyarn contact site (measured with an Ircon gauge, CH-34 series, radiation thermometer, Ircon, Inc., 207 Lawrencewood Center, Niles, Ill. 60648) is about 134C. In measuring temperature, the gauge lens is about 2 inches from the yarn and the size of the circular spot focused on is 0.045-inch in diameter, which spot is mainly on the yarn and on whatever portion of pin shows through. It should be noted that all heat is generated by the yarn-pin frictional contact, there being no heat supplied by other sources to the pin. Thermal conductivity of the pin is 8.06 X 10' Btu/ft. /sec/F./ft.

As shown in Table 4, yarn having an average crimp frequency of 34 is obtained at 2050 ypm. In a series of runs, the following data are obtained:

Run I Run 2 Run 3 Yarn speed (ypm) I300 2050 2800 Stretch over pin 2 3.4 5 Pin-filament contact (mm) 3.7 3.7 3.7 Draw-box temp. (C.) 60 92 Coefficient of friction 0.56 0.56 0.56 Ave. crimp frequency (cpi.) I2 34 38 Process efficiency 1.9 I5 24 quantity tity: [(percent stretch) (contact) (coefficient of friction) draw-box temp. X ranges between about 7.5 and 35.

It must be noted that for any given set of process conditions, the crimp frequency of yarns of the present invention increases with speed over the pin. Of course, the above variables may also be selected toproduce yarns within the scope of the invention at different speeds. A yarn speed over the pin of 2000 to 4,500 is generally used, as illustrated in the examples, but 5,000 yards per minute or higher may be desirable when high speed equipment is available.

The yarn must be drawn before the pin-treatment and preferably has a boil-off shrinkage of 5 to 25 percent. The pin-treatmentcan follow the drawing step, sequentially, in a coupled two-step process. in a preferred embodiment, yarn is spun, drawn and pintreated in a continuous, coupled process.

EXAMPLE 8 Polyethylene terephthalate of 19.5 relative viscosity (measured as described at bottom of Table l) and containing about 0.3 percent, by weight, of TiO delusterant is melt-spun at 284C. through a spinneret having 34 round holes, each hole having a diameter of 0.01 l-inch and a length of 0.020-inch. The freshly spun filaments are quenched with 23C. air crossflow against the filaments) and passed through a guide, past a finish roll to a pair of puller rolls, situated 188 inches below the spinneret and revolving at a peripheral speed of 3,398 ypm. The yarn wraps around these rolls and, subsequently, passes around rolls moving at 3,403, 3,409, and 3,413 ypm, respectively, (to maintain tension on the yarn) and passes through an interlace jet, and to a second finish roll and is then wound up at 3,41 1 yards per minute to form a package.

The interlace jet is of the type described in Bunting I et al. U.S. Pat. No. 3,115,691. The interlace jet produces an interlace pin count, as measuredaccording to Hitt U.S. Pat. No. 3,290,932, of about 20 cm.

Finish is applied at first and second finish rolls in an amount of 0.50 percent, based on the weight of the fiher. The finish is of the general type described in U.S. Pat. No. 3,594,200 to Cooley and Finch. Its composition is as followsz28 parts of coconut glycerides, 37 parts (on a wet basis) of sulfated peanut glycerides having a 20 percent water content, 25 parts of Gafac PE- 510, i.e., an acid phosphate of ethoxylated nonylphenol as depicted by the formula at Col. 2, line 5, of U.S. Pat. No. 3,594,200, and 10 parts of Shell 277 (a mixture of paraffinic and alicyclic hydrocarbons). To this mixture is added enough KOH to give a pH of 6.5.

The yarn obtained in this fashion is a 247 denier-34- filament yarn having a tensile strength of 2.47 grams per denier, an elongation of 129.1 percent, and aninitial modulus of 30.94 grams per denier. An X-raypattern of the yarn shows that it is amorphous, having no measurable crystallinity. The orientation angle is 14 and the density of the filaments is 1.342 grams per cc.

' passed in sliding contact with ice cold metal finish roll rotating in an ice/water bath. From the finish roll the cooled yarn travels a distance of less than about 8 inches to a T-pipe having a yarn passageway with a diamet'er of five-eighths inch and length of 10 inches into which atmospheric steam is fed. As the yarn passes through the pipe, it is subjected to the 100C. mixture of hot water and atmospheric steam in the pipe. Steam exits from the pipe at the entrance and exit of the yarn passageway. From the pipe, the yarn passes a distance of less than about 8 inches to a second ice cold metal finish roll rotating in bath containing a mixture of ice and water. The cooled yarn then passes to a pair of draw rolls rotating at a peripheral speed of 1,499 yards per minute, making 8-9 wraps about the rolls. In its passage from the feed rolls to the draw rolls, the yarn is drawn 1.94X. The drawn yarn has an elongation of about 13-14 percent. The yarn then passes from the draw rolls around an unheated AlSiMag 192 cream colored pin, having a smooth surface and a diameter of three-eighths-inch. The AlSiMag pin is stationary and the yarn passes over it in frictionalcontact with it at an angle of 90. From the pin the yarn passes to rolls rotating at a speed of 1,518 yards per minute making 5-6 wraps about the rolls and then to a package.

Drawing tension on the yarn as measured with a Schmidt-Waldkraiburg tension measuring device inserted in the running line is 190 grams. Yarn tension measured in the same way before and after the pin is 50-90 grams (before) 200-230 grams (after).

The properties determined on the pin-treated yarn are as follows:

Density (grams per cc): 1.364 Denier: Tenacity (gpd): 4.42 Elongation (71): 13.6 Modulus (grams per denier) 98.14 Yield Tenacity (grams per denier) 1.35 Crystallinity Index: 27-28 Orientation Angle: l4-l6 The yarn is then unwound from a package and subjected to a jet/screen relaxing treatment under the following conditions: The yarn is led to a set of feed rolls rotating at a peripheral speed of 1.,455 yards per minute, making 12 wraps about the feed rolls. From the feed rolls the yarn passes into a jet.

The jet device used is of the type described in Yngve U.S. Pat. No. 3,638,291. Referring to FIG. 2 of the Yngve patent, the dimensions of the jet are as follows:

Internal Supply Manifold 22 The jet is supplied with steam at 25 to 28 psig, and 300 to 305C. From the jet the yarn is impacted against a screen mounted on drum moving at a peripheral speed of 7 yards per minute, the drum being a 3- /2 inches wide, 15-inch diameter drum having a 60-mesh screen on itssurface. An accumulated mass of yarn travels for a distance of about 15 inches along the drum circumference. From the drum the yarn passesover guide rolls to a wind-up where it is wound up at about 1,100 yards per minute. The untwisted yarn has the following properties:

Tensile Strength (gpd) Elongation Modulus (gpd) Denier Yield Tenacity (gpd) Average Density (g. per cc.)

Crystallinity lndex Orientation Angle Additional properties are given in Table 4.

A sample of the yarn is then knit into a Swiss-pique fabric (l8-cut). The fabric has good bulk and desirable hand, texture and appearance.

Yarn Type Polymer Type Relative viscosity Feed filament cross section Feed Wheel Speed. rpm

Speed. ypm

Wraps Drawing Conditions Jet temp. (C.)

Jet press. (psig) Traversing mechanism Draw Roll Conditions Speed, rpm

Speed, ypm

Wraps Draw Box Temp. (C.) Est. Yarn Temp. (immediately before contacting pin) Draw Ratio Pin Details 1 Type Surface Size (inches) Yarn wrap angle Tension before pin (gpd) Tension after pin (gpd) Tension Change (gpd) Pin-filament contact (mm) Pulling Roll Conditions Counter reading Speed. rpm Speed. ypm Wraps Stretch (draw roll to pulling roll) Windup Conditions Counter Speed. ypm Tension (gpd) Pin textured yarn count (denier/no. filaments) TABLE 1 Ex. 1 High Shrinkage Polyethylene terephthalate. semidull 22.0 i 0.4 0.3 i 0002 round 225 85 activated same as draw box White AlSiMag 614 Matte if; X 2V. 60

Ex. 2 Medium Shrinkage Polyethylene terephthalate, semidull 22.0 i 0.4 0.3 i 0.02

round 225 85 activated same as draw box White AlSiMag 614 Matte Ya x 2% Measured at a concentration of8 grams of polymer in 100 ml. of hexafluoroisopropanol solution containing 100 ppm of H 50 at 25C.

Feed Rolls Speed (ypm) Wraps Temp. (C.) Bulking Conditions .let Used Fluid Used Fluid Temp. (C.)

TABLE l-A Coon Air 335 Pressure (psig) Relaxing Drum Screen Mesh Distance from Jet inches) Vacuum (in H O) Circumferential Speed (fpm) Yarn Residence Time on Drum (min.) Yarn Residence Length (Jet to Take-Off) on drum (inches) 7: Overfeed Feed to Drum) Let-Down Rolls Speed ypm) Wraps Overfeed (Feed Rolls to Let-Down Rolls) Yarn Tension Wind-up (g/d) about 2200 3 k *"7( Overfeed High speed-low speed/Low speed) 100) machine setting) ypm Traversing mechanism Pin Pin Surface Diameter Angle 0 Pin-filament contact (mm.) Pulling Roll Yarn Velocity (from'' setting machine) ypm Post-draw finish roll, RPM Windup tension. gpd Pin textured yarn count, (denier/no. filaments) not activated Brown AlSiMag 586 Smooth 3/ l 6" 30" Ex. 4-Medium Shrinkage Polyethylene terephthalate, semidull 20.3 i 1.5 0.3 1- 0.05 round not activated Brown AlSiM-ag 586 Smooth Measured at a concentration of 8 grams of polymer in 100 ml. of hexafluoroisopropanol solution containing 100 parts per million of H 50 at 25C.

Yarn Type Polymer Type Feed Rolls (from package) Speed (ypm) Wraps Stretch Rolls Speed (ypm) Wraps Stretch Pin Details Type TABLE 3 Size (diameter x length in inches) Pin-filament contact length (mm.)

Yarn Wrap Angle Tension (stretch) (gpd) Tension before pin (gpd) Tension after pin (gpd) Tension Change (gpd) Total tension on filaments at pin 81 Wind-Up Conditions Speed (ypm) Textured yarn count (denier/no.

filaments) Ex.5 poly( ethylene terephthalate) Brown AlSiMag 3/16 X l 3.6

(denier/no. filaments) Measured at a concentration of 8 grams of polymer in 100 m1. of hexafluoroisopropanol solution containing 100 ppm of H 50 at 25C.

7 TABLE 6 EXAMPLE 7 TABLE 4.PROPERTIES OF PRODUCTS OF EXAMPLES Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8

Before 180C. hot air treatment:

Denier/filament count 144/34 185/34 71/34 72/34 70/34 129/34 125/34 166/34 Thickness of modified portion (a) 2.3 2.1 1.6 1.4 1.4 1.9 2.9 1.5 Width (percent of filament diameter 35 45 53 49 45 46.2 46.3 54.8 Percent of filament cross-section occupied by modified portion 4.9 5.9 8.4 7.6 7.9 5 7.5 5.65 Percent of long (greater than 2 mm) discontinuities 0 25 0 7 0 0 18.7 Average length of all discontinuities (mm) 0.97 1.04 2.08 0.68 1.25 1.01 0.87 1.39 Percent of filament length occupied by discontinuities greater than 2 mm 0 0 2 0 1 0 0 3.4 After relaxation in 180C. air for mins:

Percent of filament with crimp frequency (normalized for 2.5 d.p.f.):

Greater than crimps/filament inch 99 100 100 99 100 100 100 100 Greater than crimps/filament inch... 98 100 100 99 100 100 100 100 Average crimp frequency (c.p.i.) 43 55 41 39 34 34 34 49 Crimp frequency distribution for middle 90% (Ryg tm) 40 33 27 21 n 115 14 19 RrRss/Av'r'age 0.92 0.45 0.8 0.69 0.62 0.44 0.41 0.39 Percent Coefficient of Variation 27.1 13.1 22.8 21.5 18.3 12.6 11.3 11.9

5 6 Drawing Conslitions 5e: temp. C 525 Yarn Type 6 F Polymer Type Polyethylene terephthalate, g a g g l Not mated semidull s r i eed rprb mans 3078 Relative viscosit 15 i 0.5

"rio /ii y 0.3 r 0.02 25 5 .2

Feed filament cross round Draw g Temp. (sci) 90 Seam" Est. Yarn Temp. (immedi- 90 (same as draw box) Feed wheel ately before contacting Speed. rpm 1750 pin) Speedypm 611 Draw Ratio 4.5x

p 3 30 Pin Details Dl'awmg cfngmlms Type AlSiMag 192 (Cream) Jet P- 225 Surface Smoothi Jet press. (pslg) 5 Size (inches) X 2. V2"

'lraversing mechanism Not activated Yarn wrap angle 45 Draw Roll Conditions Tension before 0.7

Speed, rpm 4205 pin (gpd) Speed. ypm 2801 Tension after 1.2 Wraps 9 15 pin (gpd) Draw Box Temp. (C.) 70 Tension change lgpd) 0.5 Est. Yarn Temp. (immedisame as draw box n-filament atcly before contacting flfl p pin) Total Tension at pin (gpd) 1.7

Draw m, 4. x Pulling Roll Conditions p Details Counter Reading 6489 Type White AlSiMag No.614 Speed, p 6489 Surface Matte p yp Size (inches) Wraps 2 Yarn Wrap angle 90 /b l li rl gb lll m" m 14% 35:3 befme pm (8) Windup Conditions 7 Tension after pin (g) 140 g Tension change (gpd) .6 enslon i Pin filame'nt All text/ure ryarn count C ta 75 i enier 1'10. laments Pun-mg R0" Conditions Measured at a concentration ofli grants of polymer ml 00 ml. of hexspeed, rpm 8875 afluogoisopropanol solution containing 100 parts per million of H 80 Speed, ypm 2902 at 25 C.

raps 3 Strfitch (dlil'aw roll to 3.6% w l i w gfi l. A textile filament having asymmetric properties 7 Counter 4430 'and an abraded surface extending along one side of the s zzzf gg count 4 filament; consisting of a single synthetic linear p0lyes-' ter composition having a minor portion distinguishable by a difference in refractive index, which extends along the abraded side of the filament with a continuity such that less than 5 percent of the filament length is occupied by discontinuities longer than 2 millimeters, the number of discontinuities longer than 2 millimeters is less than 30 percent of the total number of all discontinuities, and the average length of all discontinuities is,

less than 2 millimeters; said abraded surface of the filament being marked by closely spaced, parallel ripples which extend transversely with respect to the filament length, when viewed at high magnification after a heatrelaxing treatment for 5 minutes in C. air.

2. A textile filament as defined in claim 1 which has asymmetric shrinkage properties and develops crimp when heat-relaxed.

3. A multifilament yarn of filaments defined in claim 4. A textile filament as defined in claim 1 having a range of normalized crimp frequency values, measured after a heat-relaxing treatment for 5 minutes in 180C. air, which averages 25 to 60 crimps per filament inch with a percent coefficient of variation of less than 30.

5. A textile filament as defined in claim 4 having a range of normalized crimp frequency values which averages 30 to 60 crimps per filament inch with a percent coefficient of variation of less than 20.

6. A multifilament yarn of filaments defined in claim 4, the filament crimp being random for filament to filament.

7. A textile filament as defined in claim 4 wherein at least 95 percent of the filament length has greater than crimps per filament inch and the crimp frequency distribution for the middle 90 percent is numerically less than the average number of crimps per filament inch.

8. A textile filament as defined in claim 4 wherein the abraded surface is on the outside of crimp bends and is marked by closely spaced, parallel ripples which extend tranversely with respect to the filament length.

9. A textile filament as defined in claim 1 wherein the polyester consists essentially of polyethylene terephthalate.

10. A textile filament as defined in claim 1 which has a substantially round cross-section.

11. A textile filament as defined in claim 1 wherein said minor portion occupies from 3 percent to 20 percent of representative cross-sectional areas along the filament and is from 1 to 3 microns in thickness.

12. A textile filament as defined in claim 1 having a range of normalized crimp frequency values, measured after a heat-relaxing treatment for 5 minutes in 180C. air, wherein at least percent of the filament length has greater than l5 crimps per filament inch, at least 90 percent of the filament length as greater than 20 crimps per filament inch, and the crimp frequency distribution for the middle 90 percent is numerically less than the average number of crimps per filament inch.

13. A process for treating multifilament yarn to impart asymmetric shrinkage properties to drawn yarn filaments consisting of a single synthetic linear polyester composition which comprises passing the drawn filaments at high speed in frictional contact with an unheated nonmetallic pin for a contact distance (0) of 0.5 to 15 millimeters under a tension which applies a filament stretch (s) of 2 to 5 percent, said pin having a coefficient of friction (f) of 0.4 to 1.1 and said filaments having a temperature t) of 25 to C. just prior to contact with the pin, the values of said variables being such that (c) (s) m (t) 10 is within the range from 7.5 to 35.

14. A process for treating the filaments of a multifilament yarn as defined in claim 13, wherein said yarn has been drawn to have an elongation of 20 to 40 percent and a boil-off shrinkage of 8 to 16 percent before the yarn filaments are passed in contact with said pin.

mg I Um'rw sums ATENT OFFICE QERTIFCT @F CORECTION Patent No. 3 & 316, 992 Dated June 18, 197

Inventofls) Hans R. E. Frankfort and Peter F0 Lyons It is certified that error appears in the sbovw-idontified patent and that said Letters Patent are hereby corrected as uhown below:

Column 19, line 17,, claim 6, "for" should read Column 20, claims 13 and 1A should be deleted.

Signed and sealed this 92th day of November 1974.

(SEAL) f ttest:

McEOY M, GIBSON JR. 7 0.. MARSHALL DAN'N Attestingqgfmfiicsr Commissioner of Patents 

2. A textile filament as defined in claim 1 which has asymmetric shrinkage properties and develops crimp when heat-relaxed.
 3. A multifilament yarn of filaments defined in claim
 2. 4. A textile filament as defined in claim 1 having a range of normalized crimp frequency values, measured after a heat-relaxing treatment for 5 minutes in 180*C. air, which averages 25 to 60 crimps per filament inch with a percent coefficient of variation of less than
 30. 5. A textile filament as defined in claim 4 having a range of normalized crimp frequency values which averages 30 to 60 crimps per filament inch with a percent coefficient of variation of less than
 20. 6. A multifilament yarn of filaments defined in claim 4, the filament crimp being random for filament to filament.
 7. A textile filament as defined in claim 4 wherein at least 95 percent of thE filament length has greater than 15 crimps per filament inch and the crimp frequency distribution for the middle 90 percent is numerically less than the average number of crimps per filament inch.
 8. A textile filament as defined in claim 4 wherein the abraded surface is on the outside of crimp bends and is marked by closely spaced, parallel ripples which extend tranversely with respect to the filament length.
 9. A textile filament as defined in claim 1 wherein the polyester consists essentially of polyethylene terephthalate.
 10. A textile filament as defined in claim 1 which has a substantially round cross-section.
 11. A textile filament as defined in claim 1 wherein said minor portion occupies from 3 percent to 20 percent of representative cross-sectional areas along the filament and is from 1 to 3 microns in thickness.
 12. A textile filament as defined in claim 1 having a range of normalized crimp frequency values, measured after a heat-relaxing treatment for 5 minutes in 180*C. air, wherein at least 95 percent of the filament length has greater than 15 crimps per filament inch, at least 90 percent of the filament length as greater than 20 crimps per filament inch, and the crimp frequency distribution for the middle 90 percent is numerically less than the average number of crimps per filament inch.
 13. A process for treating multifilament yarn to impart asymmetric shrinkage properties to drawn yarn filaments consisting of a single synthetic linear polyester composition which comprises passing the drawn filaments at high speed in frictional contact with an unheated nonmetallic pin for a contact distance (c) of 0.5 to 15 millimeters under a tension which applies a filament stretch (s) of 2 to 5 percent, said pin having a coefficient of friction (f) of 0.4 to 1.1 and said filaments having a temperature (t) of 25* to 150*C. just prior to contact with the pin, the values of said variables being such that (c) (s) (f)3 (t)4 . 10 7 is within the range from 7.5 to
 35. 14. A process for treating the filaments of a multifilament yarn as defined in claim 13, wherein said yarn has been drawn to have an elongation of 20 to 40 percent and a boil-off shrinkage of 8 to 16 percent before the yarn filaments are passed in contact with said pin. 